The present invention relates to a method and apparatus for digitally processing the components of an augmentation signal as part of a multi-channel high definition television (HDTV) delivery system. Such a system has been described for example in U.S. Pat. No. 4,694,338 which is incorporated by reference herein. In such a system, an HDTV source signal, having for example a 16:9 aspect ratio and a 525 sequentially scanned or 1050, 2:1 interlaced line structure, is divided into two signals. A conventional television signal, for example an NTSC encoded signal receivable on a standard broadcast receiver, is transmitted over a regular television transmission medium, for example a standard television channel and an augmentation signal providing the additional wider aspect ratio and high resolution information of the source signal is transmitted over a second transmission medium, for example a second television channel or part of one. A high definition television receiver can then be used to receive and combine both signals into a high definition television display.